Trifluorotoluene
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| Trifluorotoluene | |
|---|---|
 |
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| Other names | Benzotrifluoride α,α,α-Trifluorotoluene |
| Identifiers | |
| CAS number | [98-08-8] |
| Properties | |
| Molecular formula | C6H5CF3 |
| Molar mass | 146.11 g/mol |
| Appearance | colorless liquid |
| Density | 1.19 g/mL at 20 °C |
| Melting point |
-29 °C |
| Boiling point |
102 °C |
| Except where noted otherwise, data are given for materials in their standard state (at 25 °C, 100 kPa) Infobox disclaimer and references |
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Trifluorotoluene is an organic compound with the formula of C6H5CF3. This colorless fluorocarbon is used as a specialty solvent in organic synthesis and an intermediate in the production of pesticides and pharmaceuticals.[1]
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[edit] Synthesis
For small-scale laboratory preparations, trifluorotoluene is synthesized by coupling an aromatic halide and trifluoromethyl iodide in the presence of a copper catalyst:[2]
- ArX + CF3I → Ar-CF3 + CuXI (where X = I, Br, Cl)
For large scale preparations using batch or continuous processes, benzotrichloride is treated with hydrogen fluoride under a pressure.[3]
- C6H5CCl3 + 3 HF → C6H5CF3 + 3 HCl
[edit] Uses
Trifluorotoluene has a variety of niche uses.
[edit] Solvent alternative to dichloromethane
According to Ogawa and Curran, trifluorotoluene is similar to dichloromethane in standard acylation, tosylation, and silylation reactions.[4] The dielectric constants for dichloromethane and trifluorotoluene are 9.04 and 9.18, respectively, indicative similar solvating properties. Dipole moments compare less favorably: 1.89 and 2.86 D for dichloromethane and trifluorotoluene, respectively. Replacing dichloromethane is advantageous when conditions require higher boiling solvents since trifluorotoluene boils 62 °C higher than dichoromethane (b.p. 40 °C).
As a solvent, trifluorotoluene is useful in mild Lewis-acid catalyzed reactions, such as the Friedel-Crafts preparations. The most common catalyst, aluminium trichloride reacts with trifluorotoluene at room temperature, however zinc chloride however does not.
[edit] Synthetic intermediate
A second and perhaps more valuable use of trifluorotoluene is as a synthetic intermediate. A derivative of trifluorotoluene, 3-aminobenzotrifluoride, is the precursor to the herbicide fluometuron, 1,1-dimethyl-3-(α,α,α-trifluoro-m-tolyl)urea.[3] It is synthesized via nitration followed by reduction to meta-H2NC6H4CF3. This aniline is then converted to the urea.
Flumetramide (6-[4-(trifluoromethyl)phenyl]morpholin-3-one), a skeletal muscle relaxant, is also prepared from trifluorotoluene.[1]
[edit] References
- ^ a b Banks, R.E. Organofluorine Chemicals and their Industrial Applications, Ellis Horwood LTD, Chichester, 1979.
- ^ Ogawa, Akiya; Tsuchii, Kaname “α,α,α-Trifluorotoluene” in Encyclopedia of Reagents for Organic Synthesis 2005, John Wiley and Sons. doi:10.1002/047084289X.rn00653 10.1002/047084289X.rn00653
- ^ a b Siegemund, Günter “Aromatic Compounds with Fluorinated Side-Chains” in Ullmann’s Encylopedia of Industrial Chemistry 2005, Wiley-VCH. doi:10.1002/14356007.a11_349.
- ^ Ogawa, Akiya; Curran, Dennis P. “Benzotrifluoride: A Useful Alternative Solvent for Organic Reactions Currently Conducted in Dichloromethane and Related Solvents” Journal of Organic Chemistry 1997, volume 62, pp. 450-451. doi:10.1021/jo9620324
